Knee and hip joint replacements. Longer lasting prostheses

Conventional hip replacement prostheses consist of a metal femoral stem and head articulating with a polyethylene acetabular component fixed to the skeleton by polymethylmethacrylate 'cement'. In these prostheses the main problems are breakdown of cement and wear of the polyethylene acetabular articulation. Particles produced by this wearing process contribute to osteolysis (bone stock loss). These problems affect the long term results of joint replacements particularly in the younger, active patients.

This article discusses new advances in prosthesis design, which reduce these problems, and techniques to overcome bone loss in revision procedures.

Improved fixation to the skeleton using cementless prostheses may improve long term results for younger, active patients. The problems of wear and osteolysis may be reduced by the utilisation of metal on metal or ceramic on ceramic articular surfaces.